Drilling straight is essential when drilling for creation of vertical (or, close to vertical) grout curtains in dams. How straight can you drill the Wassara technology holes in competent rock compared to top hammer, air hammer and diamond core drilling?

Drilling straight is essential when drilling for creation of vertical (or, close to vertical) grout curtains in dams. How straight can you drill the Wassara technology holes in competent rock compared to top hammer, air hammer and diamond core drilling?

Answer:

According to several project evaluations, you should normally obtain a deviation of less than 2%, sometimes even less than 1%. This is, of course, depending on local formation, equipment set-up and driller’s skills. Top hammer drilling normally starts deviating after 15 meters. Drilling with air-powered equipment often gives a major deviation after some dozens of meters. Compared to diamond core drilling, the Wassara technology gives same accuracy. Although, the diamond core drilling is much slower.